Fixes problem with gaussian kernel and QMLearn (#118)

Author: andersx

qml/kernels/fkernels.f90

@@ -541,7 +541,7 @@ subroutine fgaussian_kernel_symmetric(x, n, k, sigma)
 
     !$OMP PARALLEL DO PRIVATE(temp, val) SCHEDULE(dynamic)
     do i = 1, n
-        do j = 1, n
+        do j = i, n
             temp = x(:,j) - x(:,i)
             val = exp(inv_sigma * dot_product(temp,temp))
             k(j,i) = val

qml/qmlearn/kernels.py

@@ -358,9 +358,9 @@ def generate(self, X, Y=None, representation_type='molecular'):
     def _generate_molecular(self, X, Y=None):
         if Y is None or X is Y:
             # Do symmetric matrix
-            return gaussian_kernel_symmetric(X, self.sigma)
+            return gaussian_kernel_symmetric(np.array(X), self.sigma)
         else:
-            return gaussian_kernel(X, Y, self.sigma)
+            return gaussian_kernel(np.array(X), np.array(Y), self.sigma)
 
     def _generate_atomic(self, X, Y=None):